The BBC engaged in a "major breach" of broadcasting rules by not revealing that the narrator of a programme about the Gaza conflict was the son of a Hamas administrator, according to regulatory body Ofcom.
An probe by Ofcom into the programme Gaza: How to Survive a Warzone has determined that the documentary was "substantially inaccurate".
The head of the BBC had earlier expressed regret, stating there had been "a serious error in relation to truthfulness".
The authority has instructed the BBC to air a evening announcement about its findings.
"Given this constitutes a significant violation of our rules, we are directing the broadcaster to broadcast a message of our determinations against it on BBC Two at nine o'clock in the evening, with a date to be confirmed," the statement read.
'Potential to Undermine Credibility'
The regulator's announcement said: "Our probe determined that the film's lack of disclosure that the presenter's parent occupied a position in the Hamas-run government was materially misleading.
"It meant that the public did not have vital facts which may have been highly relevant to their judgment of the presenter and the content he shared.
"Trust is at the heart of the connection between a television network and its public, especially for a national broadcasting corporation such as the BBC.
"This error had the potential to damage the very considerable levels of trust that the public would have invested in a factual film from the broadcaster about the conflict in Gaza."
The film was withdrawn from the online platform in last February after the presenter's personal associations emerged, and in July an internal BBC review concluded it infringed the broadcaster's journalistic standards on accuracy.
A representative for the broadcaster commented: "The authority's determination is in agreement with the results of the internal assessment, that there was a major oversight in the programme in relation to the BBC's Editorial Guidelines on factual correctness, which corresponds to clause 2.2 of the regulator's media standards.
"We expressed regret for this and we agree with the authority's determination in full. We will adhere to the sanction as soon as the timing and language are confirmed."
